Photo-cross-linkable, insulating silk fibroin for bioelectronics with enhanced cell affinity

Bioelectronic scaffolds that support devices while promoting tissue integration could enable tissue hybrids with augmented electronic capabilities. Here, we demonstrate a photo-cross-linkable silk fibroin (PSF) derivative and investigate its structural, electrical, and chemical properties. Lithographically defined PSF films offered tunable thickness and <1-mu m spatial resolution and could be released from a relief layer yielding freestanding scaffolds with centimeter-scale uniformity. These constructs were electrically insulating; multi-electrode arrays with PSF-passivated interconnects provided stable electrophysiological readouts from HL-1 cardiac model cells, brain sli- ces, and hearts. Compared to SU8, a ubiquitous biomaterial, PSF exhibited superior affinity toward neurons which we attribute to its favorable surface charge and enhanced attachment of poly-D-lysine adhesion factors. This finding is of significant importance in bioelec- tronics, where tight junctions between devices and cell membranes are necessary for electronic communication. Collectively, our findings are generalizable to a variety of geometries, devices, and tissues, establishing PSF as a promising bioelectronic platform.